Pathology and Molecular Medicinehttp://hdl.handle.net/10523/248
Sun, 02 Aug 2015 22:25:02 GMT2015-08-02T22:25:02ZLiver Molecular Mechanisms Involved in Type 2 Diabetes: An Investigation Using Roux-en Y Gastric Bypass as a Human Model of Diabetes Remissionhttp://hdl.handle.net/10523/4899
Liver Molecular Mechanisms Involved in Type 2 Diabetes: An Investigation Using Roux-en Y Gastric Bypass as a Human Model of Diabetes Remission
2014
Besic, Vinko
Type 2 diabetes mellitus is a chronic disease characterised by progressive insulin resistance and loss of β-cell function. An incomplete understanding of its pathogenesis is hindering the effective treatment of this disease. Roux-en Y gastric bypass surgery (RYGB); however, causes rapid remission of liver insulin resistance and type 2 diabetes, and therefore affords us an opportunity to examine some fundamental characteristics of these conditions. Gathering evidence suggests that liver insulin resistance may be a crucial contributor to development of diabetes. In this thesis, we used liver biopsies taken before, and in some individuals after, RYGB surgery to explore or identify several molecular processes involved in the pathogenesis of type 2 diabetes. The study cohort included individuals with normal glucose tolerance and others with type 2 diabetes.
Ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) may cause insulin resistance through its inhibitory action on insulin signalling. This thesis provides evidence to the contrary, suggesting that liver ENPP1 is not a contributor to liver insulin resistance. We found liver ENPP1 protein abundance was lower in individuals with type 2 diabetes than in those with normal glucose tolerance, and increased after RYGB surgery in those individuals who had remission of diabetes. ENPP1 positively correlated with insulin sensitivity at the liver which is contrary to what others have reported in muscle and adipose tissue. We reasoned that our findings are likely due to the hypothesized role of ENPP1 as a natural modulator of insulin signalling and the unique role the liver has in insulin processing.
Changes in the expression ratio of insulin receptor (IR) isoform A (IR-A) and B (IRB) have previously been implicated in the pathogenesis of type 2 diabetes. The metabolically active IR-B isoform has been shown to predominate in the liver, with the liver IR-B:A ratio being reported to be 9.8. By assaying levels of IR-A and IR-B mRNA expression we found that the ratio of liver IR-B:A was abnormally low in individuals with type 2 diabetes (5.2) and increased with remission of diabetes (5.4 to 8.6). The change in ratio was due to a diminished IR-A expression following remission of diabetes. Further work with an in vitro cell model showed that insulin’s ability to inhibit gluconeogenesis in Hep G2 cells overexpressing IR-A was reduced, suggesting that the altered liver IR-B:A ratio observed in diabetes may have a detrimental effect on glucose homeostasis.
Access to liver tissue before and after RYGB surgery afforded a rare opportunity to observe changes in liver gene expression before and after remission of diabetes. Using gene microarray analysis, we showed that the majority of genes that were differentially regulated after RYGB surgery are involved in lipotoxicity, inflammation, and ER stress, particularly in those individuals who had remission of type 2 diabetes. Although there were many significant observations, the apparent inter-organ communication between the liver and the pancreas presents a hitherto unconfirmed relationship whereby the liver can not only mediate pancreatic β cell size, but can also regulate insulin secretion. This work has identified a mechanism which may be exploited to develop novel treatments for type 2 diabetes.
In conclusion this thesis describes several novel findings with respect to the pathogenesis of type 2 diabetes. It provides novel data on the role of ENPP1 and IR isoforms in insulin signalling which have furthered our understanding of the insulin signalling pathway. In addition, microarray gene analysis in liver tissue from before and after improvements in insulin resistance and remission of type 2 diabetes has allowed us to identify several candidate genes that are worthy of further investigation.
Mon, 07 Jul 2014 04:48:24 GMThttp://hdl.handle.net/10523/48992014-07-07T04:48:24ZThe protective CD4⁺ memory T cell response to tuberculosishttp://hdl.handle.net/10523/3922
The protective CD4⁺ memory T cell response to tuberculosis
2013
Ancelet, Lindsay Rae
Infection with Mycobacterium tuberculosis (Mtb), the pathogen responsible for tuberculosis (TB), results in 1.4 million deaths annually. The escalating rate of active TB, due to co-infection with HIV and emergence of antibiotic resistant Mtb strains, makes prevention of TB through the development of an effective vaccine a global health priority. The vaccine currently in use, Bacille Calmette Guérin (BCG), fails to provide reliable protection against pulmonary TB. The development of a much needed, more effective vaccine is hindered by an incomplete understanding of the memory immune response that protects against TB.
The aim of this thesis was to characterize the CD4+ memory T cell response that mediates immunity Mtb. To identify this protective response, published adoptive transfer studies had been performed using immunodeficient recipient mice and they suggested that CD62Lhi memory CD4+ T cells from BCG-vaccinated mice were key for immunity to TB. The experiments performed in this thesis demonstrate that this model is flawed; the transfer CD62Lhi CD4+ T cells from naïve or BCG-vaccinated donors into immunodeficient mice induced severe colitis in recipients and activated cells could be detected in the lungs, even in the absence of infection. The induction of colitis induced following transfer of CD62Lhi CD4+ T cells is likely to influence protection against mycobacteria and therefore the adoptive transfer of T cells into immunodeficient mice is an inadequate model to study CD4+ memory T cell-mediated immunity to TB.
A novel adoptive transfer model was established to determine the ability of CD4+ T cell subsets to protect against TB. It was hypothesized that the transfer of CD4+ T cell subsets into CD4+ T cell receptor (TCR) transgenic mice specific for an irrelevant antigen would avoid the competition observed following transfer into immunocompetent mice, permitting adoptively transferred CD4+ T cell meditated protection against TB to be observed without the induction of colitis. Adoptive transfer of BCG-experienced T cells into CD4+ TCR transgenic mice revealed that CD62Llo, and not CD62Lhi CD4+ T cells, mediated protection against lung mycobacteria, challenging the findings obtained using immunodeficient recipients. Importantly, transferred CD4+ T cells did not alter their phenotype or induce colitis in the recipient animals in the absence of mycobacterial challenge, demonstrating the adequacy of this model to evaluate CD4+ T cell elicited protection against TB.
Since effector CD62Llo CD4+ T cells could mediate immunity to mycobacteria, whether this protective subset could be generated in the lung using traditional subcutaneous (s.c) BCG vaccination and whether the protective response could be improved by mucosal BCG administration, was investigated. Comparing the immune response induced by s.c. BCG and orally delivered lipid-formulated BCG, we determined that although both administration routes were able to induce robust CD4+ effector T cell responses shortly following vaccination, superior long-term effector responses were observed in mice that received oral BCG. These results demonstrate that oral administration of BCG improves the protective immune response in the lung compared to s.c. vaccination, which could provide enhanced immunity to pulmonary TB.
The work in this thesis significantly contributes to our understanding of the CD4+ memory T cell response that protects against TB, demonstrates a means by which immunity in the lung can be improved and establishes novel models in which the ability of CD4+ T cells to protect against TB can be assessed.
Mon, 22 Apr 2013 04:21:27 GMThttp://hdl.handle.net/10523/39222013-04-22T04:21:27ZInvariant Natural Killer T Cells in Chronic Lymphocytic Leukaemiahttp://hdl.handle.net/10523/2624
Invariant Natural Killer T Cells in Chronic Lymphocytic Leukaemia
2012
Weinkove, Robert
Invariant natural killer T (iNKT) cells recognise glycolipid antigens, such as the synthetic ligand alpha galactosylceramide (a-GalCer), in the context of CD1d. Upon recognition of a-GalCer on CD1d, iNKT cells become activated and rapidly produce cytokines. Recruitment of iNKT cells with a-GalCer results in potent antitumour activity in some pre-clinical cancer models. Effector mechanisms include direct cytotoxicity of iNKT cells against CD1d-expressing tumours in the presence of a-GalCer, transactivation of natural killer cells by iNKT cell-derived interferon gamma, and iNKT cell-induced maturation and activation of dendritic cells (DCs), leading to enhanced T cell responses to DC-presented peptides.
Chronic lymphocytic leukaemia (CLL) is a clonal malignancy of B lymphocytes. Chemotherapy induces remission in most patients, but most eventually relapse. Allogeneic stem cell transplantation can be curative, but is not available to most patients due to advanced age or co-morbidities. Thus, CLL is an attractive candidate for cancer immunotherapy. This thesis aims to assess the iNKT cell/CD1d axis of patients, and to explore the possibility of exploiting iNKT cells for the immunotherapy of CLL.
Peripheral blood mononuclear cells (PBMCs) were isolated from patients with CLL, and from healthy age-matched controls, and analysed by flow cytometry. Absolute number and phenotype of circulating iNKT cells was similar in patients and controls, although patients exhibited a relative reduction in iNKT cells due to expansion of other T cell populations. iNKT cell frequency did not correlate with disease stage or with subsequent progression-free survival in patients with untreated CLL. Expression of CD1d on dendritic cells and monocytes from patients with CLL was similar to controls.
The cytokine profile of patient iNKT cells was similar to that of controls. In vitro proliferation of invariant natural killer T (iNKT) cells from patients with CLL was preserved, and iNKT cell lines generated from patients exhibited cytokine and cytotoxicity profiles similar to those from healthy controls, producing both Th1- and Th2-type cytokines, and lysing a target cell in a CD1d- and a-GalCer-dependent manner. Lysis of autologous CLL cells by iNKT cell lines was inefficient.
In vitro vaccine recall responses were enhanced by a-GalCer in PBMCs containing high frequencies of iNKT cells. The treatment of leukaemic cells with a-GalCer enhanced their ability to stimulate proliferation of allogeneic PBMCs from healthy donors in vitro, largely due to iNKT cell proliferation. Leukaemic cells treated with a-GalCer induced proliferation of autologous iNKT cells, and a-GalCer treatment also led to enhanced proliferation of ‘conventional’ T cells.
These results indicate that the iNKT cell/CD1d axis is largely intact in patients with CLL and suggest that if low iNKT cell frequencies can be overcome, the adjuvant activity of iNKT cells might be exploited in cellular immunotherapy of CLL, for example by employing a-GalCer-pulsed leukaemic cells as a whole tumour vaccine.
Mon, 19 Nov 2012 20:20:40 GMThttp://hdl.handle.net/10523/26242012-11-19T20:20:40ZRemission of Type 2 Diabetes Mellitus following Bariatric Surgery: An investigation into relevant changes in gastrointestinal physiologyhttp://hdl.handle.net/10523/2623
Remission of Type 2 Diabetes Mellitus following Bariatric Surgery: An investigation into relevant changes in gastrointestinal physiology
2012
Foo, Jonathan
A rapid remission of type 2 diabetes mellitus occurs after gastric bypass surgery in the morbidly obese however, a unifying explanation for the associated normalisation of glucose and insulin parameters of diabetes of this surgery remains uncertain. While caloric restriction and gut peptides such as GLP-1 contribute to this normalisation, they fail to explain all of the components of improved glucose control after surgery. Instead, it is likely that manipulation of the gut through bariatric surgery induces other mechanisms to effect improvement in glucose control.
Experimental work
Three experimental components were undertaken within this body of work. A clinical arm was used to examine whether intestinal gluconeogenesis or upregulation of fasting portal peptides (GLP-1, GIP and PYY) were associated with improvements in fasting glycaemia after gastric bypass. The results demonstrated that these fasting portal peptide concentrations are not significantly elevated in patients with type 2 diabetes after gastric bypass surgery despite a normalisation of fasting glucose. These studies also confirmed that portal and central venous glucose levels were not significantly different before or six days after surgery, demonstrating that intestinal gluconeogenesis was unlikely to be involved in the rapid normalisation of fasting glucose after surgery.
The animal model component of this work involved the development of an obese diabetic rat model of gastric bypass surgery. The Zucker Diabetic Fat (ZDF) rat is an obese rat strain, which may more closely model the morbidly obese individuals with type 2 diabetes who undergo gastric bypass surgery. The strain is also known for it’s peri-operative fragility that has limited its use in gastrointestinal surgery. A protocol was developed to overcome these issues and a study was performed to compare glucose control after gastric bypass or sleeve gastrectomy surgery; with pair-fed and sham-operated controls. The results demonstrated that gastric bypass surgery in this strain resulted in weight-independent and calorie-independent improvement in glucose control at one week following surgery that was not seen after sleeve gastrectomy, pair-feeding or pair-feeding with a sham-operation.
The pancreatic islets of these rats were isolated at one week following surgery to directly assess islet function. In the absence of neural or blood borne factors, islets from gastric bypass rats demonstrated a significantly higher glucose-dependent insulin secretion compared to the other groups. This suggested that an improvement in insulin-dependent glucose secretion at the β-cell might have contributed to the improvements seen in these rats after gastric bypass.
Conclusion
This dissertation contributed to the literature in several ways. The improvements in fasting glucose control after gastric bypass surgery in humans was not associated with any increase in fasting GL-1, GIP and PYY concentrations and nor was it associated with the phenomenon of intestinal gluconeogenesis. A model of gastric bypass surgery in an obese type 2 diabetic rat strain demonstrated similar early improvements in glucose control to those seen in human patients. These improvements were calorie and weight-loss independent and did not occur after a sleeve gastrectomy. After gastric bypass, rats instead demonstrated an increased glucose-dependent secretion of insulin from their isolated pancreatic islets that was neither seen in sleeve gastrectomy rats nor pair-fed controls. The direct increase in insulin secretion from islets has not previously been recognised and may be another mechanism that assists in the remission of type 2 diabetes following gastric bypass surgery.
Mon, 19 Nov 2012 20:18:50 GMThttp://hdl.handle.net/10523/26232012-11-19T20:18:50ZProteomic Identification and Immunological Validation of Protein Biomarkers for Early Detection and Prognosis of Colorectal Cancerhttp://hdl.handle.net/10523/2418
Proteomic Identification and Immunological Validation of Protein Biomarkers for Early Detection and Prognosis of Colorectal Cancer
2012
Shi, Hongjun
Colorectal cancer (CRC) is an important public health problem both internationally and in New Zealand. Currently available systems for early cancer detection (Faecal Occult Blood Test) and prediction of prognosis (pathological staging) are widely regarded as being imperfect, although no alternative tests are available. Identification and validation of sensitive and accurate biomarkers for the management of CRC is the goal of the work undertaken and described in the present PhD thesis.
Recent developments in proteomic technologies have allowed comparison of multiple proteins from different tissues to be accomplished with good reproducibility and sensitivity. This has led to identification of many putative serological and tissue biomarkers for cancer. The vast majority of these early proteomic studies used gross tumour tissues for analysis. High intratumoural tissue heterogeneity such as differences in the amount of stroma and body fluid content within the gross tissue mass makes the crude tissue lysate less representative of the epithelial cancer cells under study and increases the technical variability. The development of laser capture microdissection (LCM) has allowed isolation of pure populations of cancer cells for analysis, significantly increasing the accuracy of quantitative tumour proteomics. In this thesis, a combined use of LCM and two-dimensional difference gel electrophoresis (2D-DIGE) in profiling CRC tissues is reported. This approach greatly improved the profiling accuracy as evidenced by a significant reduction in inter-patient variation as well as the discovery and validation of six previously unrecognised CRC–associated proteins. By performing immunohistochemistry on tumour tissue microarrays, two candidate markers — ACY1 and TUFM have been further evaluated as potential novel adverse prognostic factors for CRC.
The study also developed a novel strategy to identify tumour-specific secreted proteins by incorporating secretome samples (total proteins released from cultured CRC cells) into the same 2D-DIGE analysis of the tumour tissue proteome as mentioned above. Fifteen proteins were identified to be both secreted from cancer cells and overexpressed in the tumour tissues. These tumour-specific secreted proteins have potential as specific serum/plasma markers for early cancer detection.Using an ELISA kit, developed in-house, one candidate marker — RUVBL1 was confirmed to be present in the cancer patients’ plasma at a concentration 4 fold greater on average than that found in the normal donor plasma, suggesting the potential utility of RUVBL1 as a non-invasive blood test for early detection of CRC.
These results prove that the strategy used in this study is valid in discovering potentially novel biomarkers for CRC. Studies with more participants are required to confirm the clinical utility of these findings. The biological implications of these novel candidates also need to be further explored in the future.
Fri, 03 Aug 2012 01:29:47 GMThttp://hdl.handle.net/10523/24182012-08-03T01:29:47ZAn observational study investigating the objective and subjective impact of a structured gynaecology service for women who have undergone allogeneic haematopoietic stem cell transplant.http://hdl.handle.net/10523/2339
An observational study investigating the objective and subjective impact of a structured gynaecology service for women who have undergone allogeneic haematopoietic stem cell transplant.
2012
Wood, Catherine Elizabeth
Hypothesis: The hypothesis for this study is that the provision of consultative gynaecological care and the delivery of gynaecological information to women undergoing allogeneic stem cell transplant will mean a better informed and better satisfied female transplant population. The specific aims of the study were:
1. To determine the type of information women have been given about vaginal GVHD, sexuality and fertility before they had their transplants.
2. To discover the kind of information women would like to receive about these issues before and after HSCT.
3. To assess if a gynaecology service designed especially for women undergoing HSCT is helpful with early detection and treatment of vaginal graft versus host disease.
4. To assess if a gynaecology service designed especially for women undergoing HSCT is beneficial when fertility and sexuality issues arise.
5. To discover whether the gynaecology services being provided meet the emotional, psychosocial and physical needs of the woman undergoing allogeneic stem cell transplantation.
Method: This is a retrospective observational study in which women were recruited in the following groups:
• Eligible women from Wellington Hospital who had an allogeneic haematopoietic stem cell transplant (HSCT) from 1999 to July 2004 and had no exposure to a gynaecology service.
• Eligible women from Wellington Hospital who had an allogeneic HSCT from 1 August 2004 who had exposure to a gynaecology service for HSCT recipients.
• Eligible women from the Royal Melbourne Hospital, Australia who had an allogeneic HSCT after January 1999. This group had been exposed to a gynaecology service. This group was split into two cohorts following the date lines of the Wellington cohorts. The first cohort was transplanted between 1999 and July 2004 and the second was transplanted after 1st August 2004.
This was a questionnaire-based study that asked questions about gynaecology services, genital graft versus host disease, sexuality and fertility. There was a response rate of 63% with 72 women signing consent and completing the questionnaire.
Conclusion: The results of the study showed that the provision of a gynaecology service for women pre and post HSCT was important in diagnosing and treating genital GVHD and for addressing post HSCT issues around sexuality and fertility. Significant numbers of women had problems with genital GVHD and sexuality post HSCT and better resolution of symptoms was seen in the cohorts that had exposure to gynaecology services. Women who were under the care of a structured and comprehensive HSCT related gynaecology programme were more informed and satisfied than women who did not have access to such a programme.
The study results showed that the information and education about genital GVHD, sexuality and fertility currently provided for women needs to be significantly improved and a combination of written material and verbal information developed and made available.
Fri, 06 Jul 2012 03:04:15 GMThttp://hdl.handle.net/10523/23392012-07-06T03:04:15ZThe Responses of Dental Plaque Microcosms to Experimental Environmental Changeshttp://hdl.handle.net/10523/2234
The Responses of Dental Plaque Microcosms to Experimental Environmental Changes
2012
Wall-Manning, Glenn Michael
The overall objective of this study was to increase our understanding of the compositional changes in dental plaque biofilms during and after the application of antimicrobial agents. Dental plaque contains thousands of species, and is a causative factor in dental caries and periodontal disease. Culture techniques identify only a fraction of species present as many are currently unculturable, but the development of molecular techniques such as “checkerboard DNA:DNA hybridisation” (CKB) has allowed for more comprehensive evaluations of plaque species. In this thesis, checkerboard DNA:DNA hybridization was established and refined with a panel focussed on cariogenic microbes.
In a preliminary clinical study, plaque from five oral sites was collected from 24 five-to-six year-old Christchurch children, eight caries-free (decayed, missing or filled deciduous teeth (dmft) = 0), 16 with high caries (dmft ≥5) and analysed by CKB. There were a number of caries- and site-specific composition differences with high-caries children having high levels, at specific oral sites, of Candida albicans and Lactobacillus fermentum compared to caries free children along with various other bacteria not normally associated with caries. Bacteria present at higher levels in caries-free children included most of the anaerobes in the CKB panel, but also Streptococcus mutans and Lactobacillus acidophilus. There appears to be a complex site-specific bacterial relationship to dental caries with a number of species, two in particular (Haemophilus parainfluenzae and Selenomonas noxia), associated with either high levels of caries or a caries-free state depending on the oral site sampled.
In laboratory antimicrobial investigations, dental plaque microcosms grown in an “artificial mouth” were treated with antimicrobials and analyzed by CKB to determine species profiles, with sampling immediately after treatment (day 11 or 15 of culture) then after subsequent regrowth for 7 or 15 days. The initial experiment investigated the application of the commercial mouthwashes Listerine, Plax, Savacol and Oral B to pre-formed (day 3) plaques. Subsequently, the effects of Listerine, chlorhexidine, and Savacol applied from shortly after inoculation (day 0) or to three-day-old pre-formed plaques were investigated. Plaque wet weights were determined daily to track changes in plaque biomass and CKB results were subjected to principal component analysis (PCA) and analysis of variance (ANOVA) to determine the significance of any changes observed.
Oral B had no detected effect on growth. The treatment effects of Plax (triclosan) Savacol (containing chlorhexidine) were similar, with immediate growth suppression and minimal changes in the CKB-based biofilm species composition during treatment compared to the controls. Listerine allowed composition changes during treatment and the microcosms contained more viable organisms. Stringent antimicrobials that strongly inhibited plaque growth prevented changes in the plaque microbiota by CKB analysis, but resulted in greater changes than in the Listerine-treated plaques during regrowth. These plaques tended to contain higher levels of pathogens at the end of the experiment. Saliva donor effects complicated the statistical analysis of inter-experiment species changes as the species composition changes in the biofilms appeared to be affected by the composition of the saliva inoculum, which depended on the donor used.
Mon, 23 Apr 2012 01:06:54 GMThttp://hdl.handle.net/10523/22342012-04-23T01:06:54ZRole and dynamics of yeast species in oral biofilmshttp://hdl.handle.net/10523/2142
Role and dynamics of yeast species in oral biofilms
2011
Weerasekera, Manjula Manoji
Oral biofilms are complex microbial ecosystems. In humans there are more than 900 oral microbial species, most with unknown properties or roles in disease. Candida albicans has cariogenic properties but its role in dental caries and in oral biofilms is still unclear. The incidence of oral candidosis and the involvement of non-albicans Candida species, particularly Candida dubliniensis, has recently increased due to HIV infection and immunosuppressive chemotherapy. Oral yeast identification in clinical laboratories mainly relies on culture analysis using CHROMagarTM Candida medium which yields uncertain results when differentiating C. albicans from C. dubliniensis. More reliable molecular methods for the identification of oral yeasts are needed both clinically, and for understanding oral ecosystems.
Aims: (1) To develop PCR-DGGE to presumptively identify oral yeast species, in particular to differentiate C. albicans from C. dubliniensis, and to compare its performance with CHROMagar for identification of oral yeasts. (2) To investigate yeast prevalence and diversity in saliva and oral plaque microcosms cultured from different individuals, with and without exposure to three sucrose pulses daily. (3) To identify characteristic populations of bacterial species by DGGE eubacterial fingerprinting of saliva and oral microcosm plaques derived from different individuals, and to determine if any particular population is ecologically associated with the presence and prevalence of Candida species.
Methods: PCR-DGGE and CHROMagar were evaluated for the presumptive identification of yeast species in saliva samples (n=25) and microcosm plaques (with confirmation by DNA sequencing). A range of yeast species (11 Candida species, 4 non-Candida species and 20 C. albicans isolates) were used to optimise PCR-DGGE. Previously published primer sets targeting the large subunit rDNA gene (25S–28S) (denoted primer sets N and U, respectively), and small subunit rDNA gene (18S) (primer set E) were used. Microcosm plaque biofilms were cultured from 24 individuals with and without 10% sucrose pulsing (6 minutes every 8 hour) for 11 days in a “Multiplaque Artificial Mouth”. Eubacteria were fingerprinted by PCR-DGGE.
Results: Primer set N was highly discriminatory between yeast species and showed 100% specificity in the differentiation of C. dubliniensis from C. albicans. Primer set U often produced multiple bands, and could be used to distinguish six groups of C. albicans strains. Primer set E gave poor discrimination. PCR-DGGE of saliva samples from 25 donors identified yeasts, which were not discriminated by CHROMagar, and were confirmed by sequencing. C. albicans was the predominant yeast (carriage rate 56%) followed by C. dubliniensis (16%).
In microcosm plaques, sucrose pulsing selectively promoted the growth of C. albicans and not non-albicans yeast species. No association was found between C. albicans and bacterial DGGE fingerprints of plaque microcosms. Yeasts and bacteria from different people responded differently to sucrose pulsing. Saliva bacterial clusters identified by PCR-DGGE were maintained to a significant degree during plaque microcosm development.
Conclusion: PCR-DGGE using primer set N is a specific, sensitive, economical and reproducible technique: to presumptively identify yeast species in the oral cavity; to directly differentiate important multiple yeast species in clinical specimens; and to facilitate oral microbial ecological studies.
Wed, 14 Mar 2012 20:09:30 GMThttp://hdl.handle.net/10523/21422012-03-14T20:09:30Z